How important is a good latch??

My little one is 7 weeks old and we don't have the perfect latch down pat. She loves to just suck my nipple and usually only one lip is flanged. I do unlatch her and try to get a deeper. I am going to see a lactation consultant, but I'm just wondering if I should be stressing about it. She is 7 weeks and has gained just shy of 3 pounds. She hot back up to birth weight quickly. She seems content after feedings and always passes out with milk on her face. My nipples on occasion get a little sore but not terrible. Like I said hoing to see a lactation consultant, i have been putting off and now feel guilty for not going sooner.